A power supply modulation type power amplifier (PA) receives two signals. The two signals are preferably synchronously input to the power amplifier. However, the signals pass through different signal paths and are subjected to different amounts of delay on the signal paths. Hence, to allow the two signals to be synchronously input to the power amplifier, the difference in delay between the signal paths needs to be corrected by delaying one or both of the signals.
Moreover, for various 2-input/l-output circuits including power supply modulation type power amplifiers, various characteristic differences between the signal paths of the two input signals may desirably be corrected.